Milling cutters and boring bars are tools typically used in milling machines and metalworking, wherein the milling cutters used for cutting work pieces and boring bars used to create a slot or asymmetrical hole or channel, or to create a perfect circular hole. The milling cutters generally comprise a cylindrical cutter body having a spindle on one side for attachment to a source of rotary power, and a plurality of cutting inserts mounted around the outer side of the body for cutting a work piece. The cutting inserts are typically clamped or screw-mounted into pockets present around the periphery of the cutter body. Since the pockets have to conform in part to the shape of the inserts to adequately stabilize them during a cutting operation, such milling cutters are limited in the number of types of inserts that they can use.
In order to overcome the above problem, replaceable tool cartridges have been developed in milling cutters. In such cutters, the cutting inserts are retained in a pocket present on the leading face of a tool cartridge which in turn are detachably mounted in recesses in the cutter body.
Similarly, in developing boring bar equipment it is desirable to provide rapid adjustment of indexable inserts without sacrificing accuracy due to traverse bar loading. With respect to boring bar equipment, cartridge tools are affixed to the periphery of a boring bar by screws, clamps, or wedges and which focus on the tolerance problem by affording adjustment, wherein the cartridges provide adjustment for cutting inserts.
Conventionally, during material removal operations, both milling and turning, utilizes ISO inserts, and also brazed type inserts such as tungsten carbide cutting tool inserts, PCD (Polycrystalline Diamond) inserts, CBN (Cubic boron nitride) inserts are used for cutting edges and held on holder by cartridges for clamping on the main body.
The brazed type milling cutters are directly brazed on the body of milling cutter or boring, wherein the adjustment may not be possible for run out or size on individual cutting edges. Presently, square/rectangular shaped cartridges are designed and used at present by many manufacturers with the design holding on the body of cutter by providing rectangular hole in the center of cartridges and clamping it by bold to hold with the cutter, and also height adjustment by a screw in the back side of the cartridge.
A conventional milling cartridge 100a is shown in FIG. 1.1, where in the milling cartridge includes a body 101 in rectangular shape having an elliptical bolting hole 102 for locking the cartridge using a bolt and to accommodate axial movement of the cartridges, a height setting screw 103 for adjustment and an insert 104. Another prior art cartridge 100b is shown in FIG. 1.2, which is specially developed for PCD and CBN application, and its body 101 is also in rectangular shape, locked by a bolt 105 and locked in central elliptical shaped hole 102 in the cartridge 100b. Further, the cartridge 100b is adjusted by using a height setting screw 105, wherein the adjustment would be possible only in one direction for the height of cartridges and hence the cutting edge.
In the conventional cartridges, the locking bolt hole is provided in oval shape to accommodate the height adjustment of cartridges. Moreover, the bolt hole is provided in the center of the cartridge which may weaken the cartridge. Therefore, the design of cartridge size becomes larger and can add limitation of reducing the size of the cartridges. In general, the shape of the cartridges is either square or rectangular in shape, which may lead to difficulty in achieving the accuracy in cartridge size, and also the location pocket of the cartridges can be finished only by milling operation, which is very difficult to get the accuracy from center of the cutter.
Another drawback of conventional cartridges is height adjustment can be made only in one direction, particularly cartridge can be moved only in the upward direction by rotating the screw in one direction while setting, and in case it crosses a particular limit, then the locking bolt needs to be loosened manually, brought back and once again the setting procedure needs to be repeated. Hence, it is a time consuming process and not very accurate.
Yet another drawback is that there is no location guide for locating the cartridge in same position while either changing the cartridge or replacing the cartridges and the accuracy may suffer. Especially, the milling cutter cartridges can be set or adjusted in presetter only. Therefore, the cartridges after assembling with the spindle are not possible to adjust or set which is a major drawback of the existing cartridge system.
Therefore there remains a need in the art to develop an improved cartridge in cylindrical shape for locking rigidly. Further, such cartridge design should allow to reduce the size as well allow to adjust in both direction, so that the setup time can be reduced drastically.